Show challenge when requested by server

ts/main/challengeMain.ts

@@ -0,0 +1,50 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+/* eslint-disable no-restricted-syntax, no-console */
+
+import { ipcMain as ipc, IpcMainEvent } from 'electron';
+
+import { IPCRequest, IPCResponse, ChallengeResponse } from '../challenge';
+
+export class ChallengeMainHandler {
+  private handlers: Array<(response: ChallengeResponse) => void> = [];
+
+  constructor() {
+    this.initialize();
+  }
+
+  public handleCaptcha(captcha: string): void {
+    const response: ChallengeResponse = { captcha };
+
+    const { handlers } = this;
+    this.handlers = [];
+    for (const resolve of handlers) {
+      resolve(response);
+    }
+  }
+
+  private async onRequest(
+    event: IpcMainEvent,
+    request: IPCRequest
+  ): Promise<void> {
+    console.log('Received challenge request, waiting for response');
+
+    const data = await new Promise<ChallengeResponse>(resolve => {
+      this.handlers.push(resolve);
+    });
+
+    console.log('Sending challenge response', data);
+
+    const ipcResponse: IPCResponse = {
+      seq: request.seq,
+      data,
+    };
+    event.sender.send('challenge:response', ipcResponse);
+  }
+
+  private initialize(): void {
+    ipc.on('challenge:request', (event, request) => {
+      this.onRequest(event, request);
+    });
+  }
+}